New low-alloy steel compositions and rotor shafts for electric machines made from them are described. High nickel and chromium contents ensure high strength and toughness, while other components, notably silicon and other impurities, are kept low with the result that magnetic properties remain good. One aspect provides a steel with the following proportions by weight: and the remainder substantially Fe. Other aspects are also described.
This application is a continuation application of application Ser. No. 160,651, filed Dec. 2, 1993 (now U.S. Pat. No. 5,437,742), which application is a continuation application of application Ser. No. 852,567, filed Mar. 17, 1992 (now U.S. Pat. No. 5,288,455).
A seal is provided around a shaft extending through a cavity in a hydrogen cooled generator. The seal includes a plurality of brush seal structures adapted to reduce flow to/from the cavity to a level where the risk of creating an explosive mixture of gases is minimized. In an embodiment of the invention, a series of brush seals are provided to interface with the rotary shaft so as to define a seal for minimizing the flow of hydrogen out of the cavity. In one preferred embodiment, the seal is composed of first and second brush seal assemblies, each of which is comprised of a plurality of brush seal structures. In another embodiment, spring(s) are provided to urge the brush seal structures into sealing engagement with the rotor. If deemed necessary or desirable, a vent outlet is provided in a cavity wall remote from the hydrogen atmosphere, to remove hydrogen that has leaked through the brush seals.
In a stepping motor in which a cylindrical magnet 3 which is magnetized in an axial direction is coupled with a rotary shaft and said magnet is clamped with rotor stacks 4, 5 formed by laminating annular magnetic plates the surfaces of which are electrically insulated to form a rotor, and around the outer circumference of the rotor stator cores which are wound with stator coil are disposed, a sleeve 15 is pressed in between the magnet 3 and the rotor stacks 4, 5, and the rotary shaft and interposed therebetween. The cutting operation for the outer diameter during the manufacturing processes is carried out while holding both ends of the sleeve 15, subsequently the rotary shaft is inserted, thereby, regardless of the length of the rotary shaft, the manufacturing processes are carried out to reduce the number of the molds.
In a stepping motor in which a cylindrical magnet which is magnetized in an axial direction is coupled with a rotary shaft and the magnet is clamped with rotor stacks formed by laminating annular magnetic plates, the surfaces of which are electrically insulated, to form a rotor, and around the outer circumference of the rotor stator cores which are wound with stator coil are disposed, a sleeve is pressed in between the magnet and the rotor stacks, and the rotary shaft and interposed therebetween. The cutting operation for the outer diameter of the rotor during the manufacturing processes is carried out while holding both ends of the sleeve, subsequently, the rotary shaft is inserted, thereby, regardless of the length of the rotary shaft, the manufacturing processes are carried out to reduce the number of the molds.
The bearing housing of an electrical generator is isolated from the interior of the generator enclosure by forming a cavity in the generator end wall with a seal between the generator end wall and the rotor. By sealing the bearing housing from the interior of the enclosure, the bearing housing is subject entirely to ambient pressure while the interior of the generator is subject to high vacuum pressure for cooling purposes. This isolation minimizes or eliminates potential for oil leakage into the interior of the generator previously caused by exposure on one side of the bearing housing to high vacuum pressure within the generator enclosure and the opposite side to the ambient pressure. This isolation system also eliminates the need for a high suction pressure vapor extractor and enables a conventional vapor extractor associated with the lubrication oil system to remove oil vapors from the bearing housing.
A rotor assembly and method for making the rotor assembly in which a cylindrical magnet which is magnetized in an axial direction is coupled with a rotary shaft and the magnet is clamped with rotor stacks formed by laminating annular magnetic plates, the surfaces of which are electrically insulated, to form a rotor, and around the outer circumference of the rotor stator cores which are wound with stator coil are disposed, a sleeve is pressed in between the magnet and the rotor stacks, and the rotary shaft and interposed therebetween. The cutting operation for the outer diameter of the rotor during the manufacturing processes is carried out while holding both ends of the sleeve, subsequently, the rotary shaft is inserted, thereby, regardless of the length of the rotary shaft, the manufacturing processes are carried out to reduce the number of the molds.
